Oil bearing



Nov. 7, 1933. G. B. KARELlTz 1,934,355

OIL BEARING Filed July 14, 1928 l I i l mINVENTOR George Kar'elifzATTRNl-:v

Patented Nov. 7, 1.933

UNITED sTATEs PATENT OFFICE I n l Y -,'1,9 34,355 Y i v 'v l A on.vBEARING h George B; Karelitz, Wilkinsburg, Pa., assignor to WestinghouseElectric & Manufacturing -Company, a corporation-of PennsylvanialAl-)plication July*vv l14,419.28.v 1Serial. No. 292,894 y volgens. (o1.303-7132)l My invention relates to bearings andmore par; ticularly toarmature bearings for dynamo-electric machines having considerable aXialaendthrust; as for example, for railway motors utilizing helical-thrustgears or for .other machines employed in heavy-service operations.` Itwas observed that a great number .of armature failures Were occurringin'railway :motors which were equipped with helical gears, and, inmost'instances, the specific cause was traced to the rubbing or'heatingof the thrust collar..A

In the Moore Patent No. 1,417,937, granted ionv May 30, 1922, is shown ageneral layout of a railway motor having bearing sleeves of thethrustcollar type'to which my invention is applicable. The thrust fromthe helical gear teeth may be received by the collar on either end ofthe motor, depending on the direction of rotation. :In spite of the factthat every precaution has been taken to lessen the end-thrust-and toallow, at the same end bearing. The commutator-end bearingsV fail soseldom, that, in their case, any failure may be ascribed to poormaintenanceor unavoidabledefects. The thrust load on the collar may beestimated as` 14% of the tooth load for a gear havinga tooth angle of71/2 degrees. Consequently, AWhere lubrication of the collar is verypoor, the coeicient of friction becomes very high, and overheating ofthe collar end of the bearing sleeve occurs. This heat received by thecollar is inzaddition to that created 'on the longitudinal surface ofthe shell itself. Unless some attempt is made'to decrease thecoefficient of friction on the thrust collars, bearing failures maystill be numerous.

' t is the object of my invention to produce an armature bearing whereinthe thrust collar is more effectively lubricated than has been thecasein bearings utilized heretofore. ln practicing my invention, Iprovide a passage way in the bearing shell through which oil may `be'communicated from a zone vof high hydrostaticV pressure on the bearing`A`surface to the the lineVI-VI of Fig. 5.

Vcapillary actionhfrom the oil chamber bottom of the.housing.

thrust-collarsurface, to thereby lubricate the same.` My'invention willbe better understood by referring to the. accompanying drawing, inwhich:

Figure i 'is a cross-sectional view of a'waste.- 6C! packedarmaturebea'ring, such las that-,used on railway motorsyf A l Fig. 2 isa loadingxfzliagramfork a pinion-end bearing of a railway motor; Y

f Fig. 3 is an end View` of a, pinion-endgbearing 65 sleeve of a railwaymotor, showing the distribution `of oil pressure over the` surfacethereof and embodying my invention; y

Fig. 4 is a Ilongitudinal cross-section taken on the line IVY-IVYO Fig;3; 4 Q, Figi is an endfvieivof acommutator-endbearing sleeve for arailway` motor embodying my inmention,v looking from the pinion endofthe motor, and, Y p

Fig. 6 is alongitudinal cross-section takenon VThe majority of therailway motors usedtoday employ; bearings of the waste-packed type,suchas that shown in Fig.k 1, -in which the lubricant is suppliedfto thejournal by capillary action ofthe Waste. The bearing shell or sleeve 11is supported Vin a housing 121and hasa window 13 that is inalignmentwithfthe window114-of the housing: 12

,through Whichoil is received ,from the waste disposed in the Wastechamber 15, receiving oilby 16 in the yThe,bearing surface ofthewastegpacked bearingreceives a'much smaller owof oil than ina. bearing0f the oilfring or forced-feed type, and 90 that portion-of the-surfaceon theload .line is almostv in metal-to,-inetal.,contact.` Ihehydrostatic `pressure at the` ends ofthe bearings is Vthat of theatmosphere,` but itis found that the `pressure at points in thel middleregion isvery high. The maximum pressure is reached at a :pointapproximately 2,0"l behind the loadA line or line of metaltmetalContact., u This pressure is causedaby the-motion ofthe oilin, theclearancewbetweenthe bearing shell loo vandthe journal., The oiladheres,tightlyto-the metal surface of both journal andshell andgcon..sequently, high shearing forces are-set up in the 'oil;because of itsviscosity and the. slipping of layers overeach other. l This results inconsider- 1o5 `ablehydrostatic pressure betweenv the rubbing surfaces.The intensity of the hydrostatic vpres- "sure increases with theviscosityv of the oil,with

the relative, Velocity andwith the decrease of clearance; between the`planes. windows in U0 bearing are located external of this zone ofpressure.

Since the majority of troubles due to thrust have been found in railwayapplications, particularly in those utilizing helical gears, it is myintention to illustrate the conditions found in such applications, inpreference to those found in other applications, but it will beunderstood that my invention has equal application to bearings of othertypes and to those used on motors other than those embodied in railwayequipments.

In Fig. 2, is shown a loading diagram for a pinion-end bearing when themotor is acting as a driving motor. The tooth load acts at anangle tothe tangent NN of the pitch circles of the gears, at M. Assuming thatthe pinion gear is driving in a clockwise direction, indicated by thelarrow I, the load acting on the tooth may be represented as A1, and thisload acting on the bearing may be represented by OA1, while the actingload caused by the weight of the armature may be represented by OBi, andthe resultant `of' theseV forces, OCi, acting substantially downwardly.When the helical gear is dri-ving in acounter-clockwise direction, asindicated-by the arrow II, the tooth load is partly compensated for bythe armature load, and the resultant acts in the direction OCz.

It will be noted that both of theresultants OCi and OCz act at about thesame angular distances from the vertical axis of the bearing. In suchcase, tliezonesl of hydrostatic pressure for the two directions ofrotation are found to overlap intothe same Acircumferential regions, asshown in Fig. 3, and, consequently, a' passageway 21 of my invention,disposed in a circumferential location approximately midway between thetwo resultants, will serve to lubricate a thrust-collar portion 22 forboth directions of rotation.

The maximum hydrostatic pressures, at approximately 20 behind theresultant, are found to be, at times, very high, and it does not appearto be necessary to tap at these points when pressure more removed fromthe resultant point is sufficient to positively feed oil to thethrust-collar surface. v

In Fig. 3 is illustrated a pinion-end bearing Vwhich is somewhat largerthan the commutatorend bearing in that it carries most of the toothload. It has a window 23 which is disposed in alignment with the windowof thehousing, as illustrated above, and has thepassageway 21` ofmy'invention located Aat a point at which there -is sufhcient pressurefor rotation in either direction of the shaft. A small hole 24, of about1/4 inch in diameter,` is drilled in the shell of the 'bearing at theentrance of the passageway 21 Yextending outwardly to the thrust-collarsurface.

In order to prevent wearing of the babbitt material 25 on the thrustcollar surface, the mouth 26 'of the passageway is counter-sunk.

Iii-Figs. 5 and 6, is shown the resultant forces acting on thecommutator-end bearing of a railway motor for both directions ofrotation. Since the zones cf hydrostatic pressure do not overlapeachother, it is necessary that two passageways be drilled in the shell,as is shown at 28 and 29.

Although I have described my bearing in con- A nection with a'railwaymotor, it will be understood that it may be applied to other motorswherein appreciable axial thrust causes excess heating of bearings. e

Further, IV do not'wish to be limited to the Aexact positions oftheholes, as shown in the drawing, for they may vary considerably inacvportion through said window, characterized by having means forlubricating the end-surface of the thrust'collar comprising anunobstructedpassageway through which oil may be drawn only from themiddle region of said shell surface and communicated to thethrust-collar surface, said passageway terminating, at one end, at thethrust-collar bearing surface and, at the other and, in a smooth,grooveless portion of said shell surface.

2; A waste-packed, oil-lubricated bearing for an armature axle shaft ofYa geared motor having axial .thrust thereon, comprising a bearingsleeve having av thrust-collar portion adapted to wear against a flangeportion on said shaft, characterized by the fact that said sleeveV hasan unobstructed passageway which conducts oil onlyV from a zone of highhydrostatic pressure within said bearing at an ungrooved portion thereofto the wearing surfaces of said flange and said: thrust collar. u 3. Incombination with a shaft and an oilbearing sleeve having a thrust-collarportion, means for lubricating the journal surfaces between said shaftand said sleeve, the pressure of oil within( an ungrooved surface ofsaid sleeve when said: shaft is rotating in a given direction beinghighest at approximately 20 degrees behind the load line, and means fortapping only saidzone of high pressure wherebyoil maybe positively. fedto thef surface of the thrust-collar portion.

.4..v In combination with a shaft. and an'oilbearing sleeve .having athrust collar portion, means" for lubricating the journal surfacesbetween said. shaftand said sleeve, the pressure of oil within saidsleeve, when said shaft is rotating in either direction, being built upin an ungrooved zone behind-the load line, and said sleeveVoil-supplying means for lubricating the journal surface, characterizedby Ya holein a smooth,

ungrooved journal surface at a point which is removed from'theendsof'the bearing and from saidfcapillary oil-supplying means'a'nd atwhich a material 'oils-pressure exists, and passageway meanscommunicating with said hole and constituting meansffor positivelyfeeding oil from said oils'pr'essure point of the thrust-bearingsurface. Y

'6. A rotating shaft for translating mechanical power provided with abearing having. journal and thrust-bearing surfaces and with capillaryoilfsupplying means for lubricating the journal surface, characterizedby the fact that said bearing has substantially non-overlappingoil-pressure zones for different directions of rotation, andcharacterized further by a plurality of holes in a smooth, ungroovedjournal surface at points removed from the ends of the bearing and fromsaid capillary oil-supplying means and including at least one hole in asubstantial oil-pressure area for each direction of rotation, andpassageway means communicating with said holes and constituting meansfor positively feeding oil from 'said oil-pressure areas to thethrust-bearing surface. n '7. In combination with a shaft and anoilbearing sleeve having a thrust-collar portion, means for lubricatingthe journal surfaces between said shaft and said sleeve, the pressure ofoil within said sleeve, when said shaft is rotating in either direction,being built up in an ungrooved zone behind the vload line, and saidsleeve having a plurality of holes for conducting to the thrust-collarsurfaces only from said zone in the journal surfaces in order to sustainan oil flow upon shifting of the load line.

GEORGE B. KARELITZ.

